Peer Reviewed Publications on the Safety
of GM Foods

Results of a search of the PubMed
database for publications on feeding studies for GM crops.

By Dr. Christopher Preston,
Senior Lecturer in Weed Management,
University of Adelaide;
christopher.preston@adelaide.edu.au

Introduction

There has been considerable recent comment on the lack of peer-reviewed
scientific studies on the effect of GM food and feed on livestock, other
animals and humans. A report by Pryme and Lembcke (2003) described 10
such studies. This report and the small number of studies is often quoted
by groups opposed to the use of GM crops as justification for banning
their use in the food chain. To determine the current state of the literature,
I conducted a search of the PubMed database for publications on this topic.

Methods

The search strategy I used included the search terms (genetically and
modified and food) coupled with crop species with known genetic modifications,
including maize, soybean, canola, cotton, potatoes, tomatoes and peas.
Searches also included the word transgenic instead of genetically and
modified. A large number of hits were obtained by this search strategy,
with most having little or nothing to do with GM food tests.

I collected papers that had:

1. An abstract in PubMed;

2. Were a research publication, not a review or commentary

3. Reported a feeding study involving food or food products from GM crops
(not purified proteins from other sources such as bacteria or other GM
products) in the abstract;

4. Test subjects were mammals, birds or fish; and 5. Reported at least
one measure of comparison with non-GM food.

Results

In all, 42 publications abstracted in PubMed passed these tests. The
search strategy extracted most of the studies covered by Pryme and Lembcke
(2003). The ones absent were not apparently abstracted in PubMed (e.g.
Pusztai 1998) or were reviews (Pusztai 2002). My search uncovered several
publications between 1999 and 2001 that were not captured by Pryme and
Lembcke (2003).

Of the 42 publications, most examined the effects of feeding GM crop
products to livestock including cattle, pigs and poultry. A smaller number
examined effects on rats and mice with two on fish. As reported in the
abstracts of the publications, 36 studies found no significant effect
of GM crop products on the parameters measured or concluded GM and non-GM
products were equivalent. Four studies reported a positive effect of the
GM feed (however, two of these were GM plants engineered for improved
food quality) and two reported negative effects. The studies reporting
negative effects were published in 1998 and 1999 (references 3 and 4 in
the list). Since 2000, 35 publications have reported no important differences
or positive effects of feeding GM crops.

Almost two thirds (27) the publications extracted from the database have
been published since 2002. Many of these examined the potential effects
of GM crop on livestock performance and were clearly aimed at determining
whether the reports of dangers of GM crops to livestock in the press were
true.

Conclusions

There are at least 42 publications extractable from the PubMed database
that describe research reports of feeding studies of GM feed or food products
derived from GM crops. The overwhelming majority of publications report
that GM feed and food produced no significant differences in the test
animals. The two studies reporting negative results were published in
1998 and 1999 and no confirmation of these effects have since been published.
Many studies have been published since 2002 and all have reported no negative
impact of feeding GM feed to the test species.